1. Field of the Invention
The present invention relates to apparatus and methods for measuring the volume of liquid in a container. More particularly, the present invention relates to devices that are particularly configured for the measurement of a volume of beer within a keg. Additionally, the present invention relates to techniques for measuring liquid volume based on pressure differentials and/or combined with a flow meter.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
In the bar and restaurant industry, an accurate inventory is paramount to maintaining the bottom line and anticipated profit margins. When food and drink inventory are lost, it eats into the company's profit. Accordingly, restaurant owners and operators employ strict inventory tracking methods for food, liquor and controllables. For instance, food consumption is measured by noting counts per unit or weighing the food product. Specific emphasis is placed on the amount of pounds and ounces being sold and lost. Inventory for controllables, such as paper goods, condiments, glassware and miscellaneous items are also routinely counted. Liquor is accounted for by counting bottles and noting levels remaining in partially used bottles. Most bar inventory methods count the bottles in tenths or quarters. This measuring technique is reasonably accurate since the liquor levels can be seen through the bottles. While accountable inventory measuring techniques exist for food, liquor and controllables, there is still no accurate, cost effective method or device for taking the inventory of draft beer in a closed keg.
Conventional techniques for taking inventory of draft beer are either inaccurate, unsafe, time-consuming and/or too expensive. Draft beer is sold in opaque kegs. Therefore, beer levels cannot be readily and accurately ascertained. Inventory for draft beer is primarily done by lifting and shaking the keg. Lifting and shaking kegs to determine the quantity remaining is highly subjective and inaccurate. It only provides an approximation of how much beer is left in the keg. Another method involves lifting and weighing the keg to determine the amount of beer remaining Weighing the keg, while theoretically more accurate, requires a durable scale and additional information for converting weight to ounces. Additionally, errors can be made in weighing the keg when objects are placed upon the keg during the measurement. Neither method is convenient and both involve heavy lifting. Since a full keg weighs approximately 160 pounds, there is a high risk of back injuries, muscle tears and hernias, associated with lifting, shaking and/or weighing kegs, even with a partially filled keg. An injured employee is inevitably lost for a period of time and a worker's compensation claim is invariably made, increasing the likelihood of increased insurance premiums.
Often, the most common method for measuring the beer in a keg that does not involve the lifting of the keg is simply to shake or kick the keg. This approach is extremely inaccurate. Alternatively, a flow meter can be used to measure the flow of beer through the beer line. This will measure the amount of beer consumed, from which the remainder of the keg can be inferred. Unfortunately, these flow meters must be manually reset when the keg is replaced. This introduces user error and is not cost effective.
Industry-wide, it has been found that beer distributors do not know the inventory of the customer and, thus, their product fulfillment needs. Systems that employ long beer lines have substantial foaming issues when the keg is allowed to go empty and the beer line fills with air. Foam wastes product and diverts employee time from serving customers. Most draft beer systems are prone to employee theft. Refrigeration space is expensive. As such, it is desirable to avoid unnecessary inventory. Under those circumstances where the keg runs empty, sales of such a particular beer product will not occur. The carbon dioxide is lost when the employee pulls a tap and there is no beer remaining in the lines. As such, this carbon dioxide is wasted.
As such, it is desirable to have a system that measures the liquid levels within a keg that does not involve kicking, lifting, shaking or weighing. Additionally, it is desirable to have a system for measuring the liquid levels in kegs that can be remotely accessed.
In the past, various patents have issued relating to devices for measuring liquid levels in a container. U.S. Pat. No. 698,334, issued on Apr. 22, 1902 to J. D. Smith, is an early patent for a spring scale that is used to measure the weight of a keg. A vertically-movable platform supports the keg. The level of the keg will rise as the liquid within the keg is depleted. The rising of the platform will provide an indication of the level of liquid within the keg. Additionally, a gauge is provided which provides an assessment of the number of gallons remaining in the keg.
U.S. Pat. No. 2,127,875, issued on Aug. 23, 1938 to Lippert et al., teaches a dispensing gauge. A metallic draft pipe is immersed within the liquid within the keg. The metallic draft pipe has a longitudinal groove extending from end to the other. A longitudinal electrode is mounted in the groove and insulated from the draft pipe. The electrode and the draft pipe are exposed to the liquid.
U.S. Pat. No. 3,696,675, issued on Oct. 10, 1972 to A. S. Gilmour, describes an apparatus and method for externally determining the level of a mass of flowable material, such as liquid or granular material, contained in a closed or sealed container. This is an apparatus of elongated strip of material coated or embedded with cholesteric liquid crystals which vary chromatically with variations in temperature. The elongated strip is applied to the outer surface of the wall of the container in heat-conducting relationship thereto and extends along the height of the container. Because of the difference in the rate of heat conduction of the void volume and the filled space of the container, the container wall will experience a temperature radiant which is pronounced at the interface of the contents. The change in temperature is readily discernable visually because of the abrupt change in color of the elongated strip at the material interface. As such, it permits an observer to readily detect the level of the contents in the container.
U.S. Pat. No. 3,956,934, issued on May 18, 1976 to J. M. White, shows a liquid level indicator for a pressurized liquid container, such as a keg. The keg has an outlet arranged to be connected to a dispensing conduit for conducting the liquid from the container to the point of use at a remote location. This outlet includes a gauge tube of transparent material having a check valve therein. The level of liquid in the gauge tube continuously corresponds to the level of liquid in the container. The check valve and the gauge tube maintain liquid in the gauge tube during the dispensing of the liquid from the container through the dispensing conduit.
U.S. Pat. No. 4,220,048, issued on Sep. 2, 1980 to Greciotis et al., teaches a cooler and level indicator for beer kegs. In particular, there is an insulated container for holding iced water in contact with a keg of beer. An insulated cover seals the container. An externally readable level gauge provides an indication of the iced water level. This level is proportional to the amount of beer remaining in the keg after the keg becomes buoyant.
U.S. Pat. No. 6,260,414 issued on Jul. 17, 2001 to Brown et al., describes liquid crystal liquid level indicator for use with a keg. The crystal fluid level indicator is placed in thermal contact with the exterior surface of the keg. This indicator produces a color change that is a function of the liquid temperature when the liquid is within a predetermined temperature range. The indicator is a multiple level strip having a top transparent layer, a liquid crystal layer, a black background layer, and an attachment layer employing a protected adhesive on its bottom surface for removably attaching the strip to the keg.
U.S. Pat. No. 6,925,872, issued on Aug. 9, 2005 to A. J. Hadala, provides a temperature-sensing device for determining the level of a fluid in a container. This device is based upon the fact that a beverage container containing a liquid will absorb heat energy from the surrounding environment at a greater rate than a gaseous component in the headspace of the beverage container. As the liquid is drawn from a beverage container, a greater headspace results. The measuring device is employed along the height of the keg such that the volume may be determined by observing the difference in the temperature along the height of the container. U.S. Pat. No. 7,302,846, issued on Dec. 4, 2007 also to A. J. Hadala, shows a similar structure.
U.S. Pat. No. 7,810,679, issued on Oct. 12, 2010 to Wauters et al., teaches a home beer dispensing apparatus that has a keg with a self-contained bag filled with a beer and a pressure system. The pressure system creates a pressurized air space between the keg inner walls and the bag to assist in the dispensing of the beer. The apparatus also has a pressure sensing system adapted to measure the time rate of pressure change in the keg. A signaling device is responsive to the time rate of pressure change in the keg to produce a signal related to the volume of beer remaining the keg. The signal is displayed visually on the dispensing apparatus.
It is an object of the present invention to provide a system for the measuring of a volume of liquid in a keg that effectively measures the volume of liquid remaining in the keg.
It is another object of the present invention to provide a system for the measuring the volume of liquid in a keg that does not require modification in the structure of the keg itself.
It is still another object of the present invention to provide a system for measuring the volume of liquid in a keg that relies on pressure differentials between the liquid pressure and the gas pressure to determine the volume of liquid in the keg.
It is another object of the present invention to provide a system for the measuring of a volume of liquid in a keg that allows for the remote accessing of the volume information.
It is further object of the present invention to provide a system for the measuring of a volume of liquid in a keg which easy to use, easy to install, and relatively inexpensive.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.